Clear silicone microemulsions formed spontaneously

ABSTRACT

Clear microemulsions are formed spontaneously without mixing, stirring, shearing, or input of mechanical energy for agitating ingredients used in making microemulsions, by simply combining (i) water; (ii) a volatile siloxane; (iii) a long chain or high molecular weight silicone polyether; and, as an optional ingredient, (iv) a cosurfactant such as a monohydroxy alcohol, an organic diol, an organic triol, an organic tetraol, a silicone diol, a silicone triol, a silicone tetraol, and a nonionic organic surfactant. In an alternate embodiment, a non-volatile siloxane is included as an ingredient, and the silicone polyether is a long chain or high molecular weight silicone polyether, or a short chain or low molecular weight silicone polyether.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

[0003] Not applicable.

FIELD OF THE INVENTION

[0004] This invention is related to clear silicone microemulsions thatform spontaneously without input of significant mechanical energy, andmore particularly to the use of certain longer chain, higher molecularweight species of silicone polyether (SPE) as primary surfactant. Theycan also be used in forming clear silicone microemulsions containing oilphases consisting of mixtures of volatile as well as nonvolatilesilicone oils.

BACKGROUND OF THE INVENTION

[0005] Microemulsions are clear or transparent because they containparticles smaller than the wavelength of visible light, i.e., typically10-100 nanometer. They can contain oil droplets dispersed in water(O/W), water droplets dispersed in oil (W/O), or they may bebi-continuous in their structure. They are characterized by ultra lowinterfacial tension between oil and water phases.

[0006] While U.S. Pat. No. 5,705,562 (Jan. 6, 1998) teach the use ofshort chain or low molecular weight silicone polyethers in preparationof spontaneously formed clear silicone microemulsions, they do not teachpreparing clear silicone microemulsions using long chain or highmolecular weight silicone polyethers. This is not surprising as prior tothis invention, there is nothing in the public domain relative to thepreparation of clear silicone microemulsions using long chain or highmolecular weight silicone polyethers.

[0007] The '562 patent, unlike the present invention, also fails toteach preparation of clear microemulsions from mixtures of both avolatile silicone oil and a nonvolatile silicone oil. Rather, the clearsilicone microemulsions in the '562 patent are limited to oil phasescontaining only silicone oils which are volatile.

[0008] As a third distinction, according to the '562 patent, thecomposition should be free of non-essential ingredients such ascosurfactants. According to this invention, however, the composition maycontain such non-essential cosurfactants, yet result in formation ofclear silicone microemulsions.

BRIEF SUMMARY OF THE INVENTION

[0009] The invention relates to a method of spontaneously forming aclear microemulsion without mixing, stirring, shearing, or input ofmechanical energy for agitating ingredients used in makingmicroemulsions, by simply combining as ingredients (i) water; (ii) avolatile siloxane; (iii) a long chain or high molecular weight siliconepolyether; and, as an optional ingredient, (iv) a cosurfactant such as amonohydroxy alcohol, an organic diol, an organic triol, an organictetraol, a silicone diol, a silicone triol, a silicone tetraol, and anonionic organic surfactant.

[0010] In this embodiment, the long chain or high molecular weightsilicone polyether is a polymer having formula

[0011] where R1 represents an alkyl group containing 1-6 carbon atoms;

[0012] R2 represents the radical —(CH₂)_(a)O(C₂H₄O)_(b)(C₃H₆O)_(c)R3; xis 20-1,000; y is 2-500; z is 2-500; a is 3-6; b is 4-20; c is 0-5; andR3 is hydrogen, a methyl radical, or an acyl radical.

[0013] In an alternate embodiment, the invention relates to a method ofspontaneously forming a clear microemulsion without mixing, stirring,shearing, or input of mechanical energy for agitating ingredients usedin making microemulsions, by simply combining as ingredients (i) water;(ii) a volatile siloxane; (iii) a non-volatile siloxane; (iv) a siliconepolyether; and, as an optional ingredient, (v) a cosurfactant such as amonohydroxy alcohol, an organic diol, an organic triol, an organictetraol, a silicone diol, a silicone triol, a silicone tetraol, and anonionic organic surfactant.

[0014] A long chain or high molecular weight silicone polyether, or ashort chain or low molecular weight silicone polyether can be used inthis alternate embodiment.

[0015] Clear microemulsions prepared according to either method are alsoa feature of the invention.

[0016] These and other features of the invention will become apparentfrom a consideration of the detailed description.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0017] Not applicable.

DETAILED DESCRIPTION OF THE INVENTION

[0018] In a first embodiment of the invention, clear microemulsions areformed by simply combining the components (i) water; (ii) a volatilesiloxane; (iii) a long chain or high molecular weight siliconepolyether; and, as an optional component, (iv) a cosurfactant such as amonohydroxy alcohol, an organic diol, organic triol, organic tetraol,silicone diol, silicone triol, silicone tetraol, or nonionic organicsurfactant.

[0019] Some representative examples of the optional cosurfactantcomponent (iv) include monohydroxy alcohols such as methanol, ethanol,and 2-propanol; organic diols such as ethylene glycol and propyleneglycol; organic triols such as glycerol; organic tetraols such aspentaerythritol and 1,2,3,6-hexane tetraol; and a silicone tetraol suchas shown below.

[0020] The nonionic surfactant should be a non-silicon atom containingnonionic emulsifier. Most preferred are alcohol ethoxylatesR4-(OCH₂CH₂)_(d)OH, most particularly fatty alcohol ethoxylates. Fattyalcohol ethoxylates typically contain the characteristic group—(OCH₂CH₂)_(d)OH which is attached to fatty hydrocarbon residue R4 whichcontains about eight to about twenty carbon atoms, such as lauryl (C₁₂),cetyl (C₁₆) and stearyl (C₁₈). While the value of “d” may range from 1to about 100, its value is typically in the range of 2 to 40. Someexamples of suitable nonionic surfactants are polyoxyethylene (4) laurylether, polyoxyethylene (5) lauryl ether, polyoxyethylene (23) laurylether, polyoxyethylene (2) cetyl ether, polyoxyethylene (10) cetylether, polyoxyethylene (20) cetyl ether, polyoxyethylene (2) stearylether, polyoxyethylene (10) stearyl ether, polyoxyethylene (20) stearylether, polyoxyethylene (21) stearyl ether, polyoxyethylene (100) stearylether, polyoxyethylene (2) oleyl ether, and polyoxyethylene (10) oleylether. These and other fatty alcohol ethoxylates are commerciallyavailable under names such as ALFONIC®, ARLACEL, BRIJ, GENAPOL®,LUTENSOL, NEODOL®, RENEX, SOFTANOL, SURFONIC®, TERGITOL®, TRYCOL, andVOLPO.

[0021] Compositions according to this embodiment of invention contain5-90 percent by weight of surfactant, preferably 15-50 percent byweight. The balance of the composition is oil and water, with theproportions of oil and water generally being in the ratios of 5:95 to95:5, respectively.

[0022] In a second embodiment of the invention, clear microemulsion areformed by simply combining the components (i) water; (ii) a volatilesiloxane; (iii) a nonvolatile siloxane; (iv) a silicone polyether; andas an optional component, (v) a cosurfactant such as a monohydroxyalcohol, an organic diol, an organic triol, an organic tetraol, asilicone diol, silicone triol, silicone tetraol, or a nonionic organicsurfactants.

[0023] Compositions according to this embodiment of the inventioncontain 5-90 percent by weight of surfactant, preferably 15-50 percentby weight. The balance of the composition is oil and water, inproportions of oil and water generally in the ratios of 5:95 to 95:5.The nonvolatile silicone oil in the mixed oil phase constitutes 1-30percent of the oil component.

[0024] The long chain or high molecular weight silicone polyether canhave a structure represented by:

[0025] A cyclic polyether of the type shown below can also be used.

[0026] In these structures, R1 represents an alkyl group containing 1-6carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, and hexyl; R2represents the radical —(CH₂)_(a)O(C₂H₄O)_(b)(C₃H₆O)_(c)R3; x has avalue of 20-1,000; y has a value of 2-500 z has a value of 2-500; m hasa value of 3-5; n is one; a has a value of 3-6; b has a value of 4-20; chas a value of 0-5; and R3 is hydrogen, a methyl radical, or an acylradical such as acetyl. Preferably, R1 is methyl; b is 6-12; c is zero;and R3 is hydrogen.

[0027] Silicone oils suitable for use in making clear siliconemicroemulsions according to this invention include both volatile andnonvolatile linear and cyclic methyl, higher alkyl, or aryl siloxanes.

[0028] The volatile linear methyl siloxanes have the formula(CH₃)₃SiO{(CH₃)₂SiO}_(k)Si(CH₃)₃. The value of k is 0-5. The volatilecyclic methyl siloxanes have the formula {(CH₃)₂SiO}_(t). The value of tis 3-9. Preferably, these volatile polydimethylsiloxanes have a boilingpoint less than about 250° C. and viscosity of about 0.65 to about 5.0mm²/s.

[0029] Some representative volatile linear methyl siloxanes arehexamethyldisiloxane (MM) with a boiling point of 100° C., viscosity of0.65 mm²/s, and formula Me₃SiOSiMe₃; octamethyltrisiloxane (MDM) with aboiling point of 152° C., viscosity of 1.04 mm²/s, and formulaMe₃SiOMe₂SiOSiMe₃; decamethyltetrasiloxane (MD₂M) with a boiling pointof 194° C., viscosity of 1.53 mm²/s, and formula Me₃SiO(Me₂SiO)₂SiMe₃;dodecamethylpentasiloxane (MD₃M) with a boiling point of 229° C.,viscosity of 2.06 mm²/s, and formula Me₃SiO(Me₂SiO)₃SiMe₃;tetradecamethylhexasiloxane (MD₄M) with a boiling point of 245° C.,viscosity of 2.63 mm²/s, and formula Me₃SiO(Me₂SiO)₄SiMe₃; andhexadecamethylheptasiloxane (MD₅M) with a boiling point of 270° C.,viscosity of 3.24 mm²/s, and formula Me₃SiO(Me₂SiO)₅SiMe₃.

[0030] Some representative volatile cyclic methyl siloxanes arehexamethylcyclotrisiloxane (D₃) a solid with a boiling point of 134° C.and formula {(Me₂)SiO}₃; octamethylcyclotetrasiloxane (D₄) with aboiling point of 176° C., viscosity of 2.3 mm²/s, and formula{(Me₂)SiO}₄; decamethylcyclopentasiloxane (D₅) with a boiling point of210° C., viscosity of 3.87 mm²/s, and formula {(Me₂)SiO}₅; anddodecamethylcyclohexasiloxane (D₆) with a boiling point of 245° C.,viscosity of 6.62 mm²/s, and formula {(Me₂)SiO}₆.

[0031] The nonvolatile linear and cyclic higher alkyl and aryl siloxanesare represented respectively by the formulas R^(a) ₃SiO(R^(a)₂SiO)_(p)SiR^(a) ₃ and (R^(a) ₂SiO)_(r). R^(a) can be an alkyl groupwith 1-20 carbon atoms, or an aryl group such as phenyl. R^(a) can alsobe hydrogen, an aralkyl (arylalkyl) group such as benzyl, or an alkaryl(alkylaryl) group such as tolyl. The value of p is 0-80, preferably5-20. The value of r is 3-9, preferably 4-6. These polysiloxanesgenerally have a viscosity in the range of about 5-100 mm²/s.

[0032] Nonvolatile polysiloxanes can also be used where p has a valuesufficient to provide siloxane polymers with a viscosity in the range ofabout 100-1,000 mm²/sec. Typically, p can be about 80-375. Illustrativeof such polysiloxanes are polydimethylsiloxane, polydiethylsiloxane,polymethylethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane,and polymethylhydrogensiloxane.

EXAMPLES

[0033] The following examples are set forth in order to illustrate theinvention in more detail. In these examples, the symbol M is used toindicate the monofunctional polyorganosiloxane structural unitR₃SiO_(1/2), while the symbol D is used to indicate the difunctionalpolyorganosiloxane structural unit R₂SiO_(2/2).

Example 1 Preparation of Single Phase Oil and Water Compositions withPolymeric Silicone Surfactants

[0034] A 60/40, 70/30 and 80/20 mixture of silicone polyether (SPE), and1,2-hexanediol were each prepared by heating the SPE for 45 seconds in amicrowave oven, and then adding 1,2-hexanediol. The mixtures were shakenand spun on the rotary wheel of a Model 7637-01 Roto-Torque device forthirty minutes. The mixtures were all used at room temperature.

[0035] For each sample, a triangular graph was used to determine thedesired percentages of each of the three components to be used. Using aMettler AG204 analytical balance, samples with a total mass of threegram were prepared. For example, 1.65 g of surfactant (60/40) was firstweighed into a 13×100 mm Pyrex tube vial, 1.215 g of deionized water wasadded, and finally 0.135 g of volatile siloxane D₅. Other samplesprepared included (i) 1.5 g of surfactant (70/30), 1.35 g of deionizedwater, and 0.15 g of D₅ fluid; and (ii) 1.5 g of surfactant (80/20),1.35 g of deionized water, and 0.15 g of D₅ fluid. The sample tube vialswere each labeled and spun on the rotary wheel for ten minutes. Allformed clear microemulsions.

[0036] Microemulsions were also formed using an SPE, diethylene glycolmonohexyl ether, D₅ fluid, and deionized water. The best results wereobtained using compositions comprising (i) 1.5 g of the 50/50surfactant, 0.15 g of D₅ fluid, and 1.35 g of water; (ii) 0.6 g of 50/50surfactant, 0.24 g D₅ fluid, and 2.16 g of water; and (ii) 1.8 g of50/50 surfactant, 0.6 g of D₅ fluid, and 0.6 g of water. TABLE 1 PercentSurfactant % H₂O Percent Oil Appearance 55% SPE/1,2-hexanediol (60/40)40.50 4.5% D₅ fluid Clear 50% SPE/1,2-hexanediol (70/30) 45     5% D₅fluid Clear 50% SPE/1,2-hexanediol (30/20) 45     5% D₅ fluid Clear 50%SPE/C₆E₂ (50/50) 45     5% D₅ fluid Clear 20% SPE/C₆E₂ (50/50) 72     8%D₅ fluid Clear 60% SPE/C₆E₂ (50/50) 20    20% D₅ fluid Clear

[0037] In this example and in Table 1, SPE represents the long chain orhigh molecular weight silicone polyether (SPE) with a structurecorresponding to MD₂₂D′(EO₁₂)₂M. C₆E₂ represents the nonioniccosurfactant diethylene glycol monohexyl ether. D₅ is the volatilesiloxane decamethylcyclopentasiloxane.

Examples 2 to 4 Preparation of Single Phase Oil and Water CompositionsUsing Mixtures Containing Low and High Molecular Weight Silicone Oils

[0038] In these examples, microemulsions were prepared using the shortchain or low molecular weight SPE surfactant MD′(EO₇)M, and the othercomponents shown below in Tables 2-4. TABLE 2 Example 2—MicroemulsionsFormed at 39-70° C. Component Actual Weight, gram Surfactant, MD′ (EO₇)M1.0498 Oil, Decamethylcyclopentasiloxane 0.6276 Oil,Polydimethylsiloxane, 10 cs 0.1558 Water 1.1704

[0039] TABLE 3 Example 3—Microemulsions Formed at 41-75° C. ComponentActual Weight, gram Surfactant, MD′ (EO₇)M 0.9031 Oil,Decamethylcyclopentasiloxane 0.6293 Oil, Polymethylhydrogensiloxane0.2106 Water 1.2613

[0040] The polymethylhydrogensiloxane oil used in Example 3 and shown inTable 3 was a nonvolatile siloxane, and consisted of a trimethylsiloxyendblocked dimethyl methylhydrogen siloxane polymer with a viscosity ofabout 7 centistoke. It had a structure generally represented byMD_(8.7)D^(H) _(3.7)M. TABLE 4 Example 4—Microemulsions Formed at 35-45°C. Component Actual Weight, gram Surfactant, MD′ (EO₇)M 1.0514 Oil,Decamethylcyclopentasiloxane 0.7413 Oil, Polydimethylsiloxane, 50 cs0.04  Water 1.1733

Example 5 Preparation of Microemulsion with ABA Type SPE

[0041] Six gram of a non-crosslinked and long chain or high molecularweight silicone polyether of the formula M′D₅₀M′ wherein M′ represents(CH₃)₂[(CH₂)₃₀(CH₂CH₂O)₇H]SiO— and D is (CH₃)₂SiO═; 2.0 gram of thevolatile silicone oil D5, i.e. decamethylcyclopentasiloxane, were loadedinto a plastic container and mixed with a dental mixer for 20 seconds.Two gram of deionized water was added and mixed with the dental mixerfor 20 seconds, resulting in a clear gel.

Example 6 Preparation of Microemulsion with Rake Type SPE 1

[0042] 5.05 gram of a non-crosslinked and long chain or high molecularweight silicone polyether of the formula MD₂₂D′₂M wherein M represents(CH₃)₃SiO—, D is (CH₃)₂SiO═, and D′ represents(CH₃)[(CH₂)₃₀(CH₂CH₂O)₇H]SiO═; and 2.83 gram of volatile silicone oilD5, were loaded into a plastic container and mixed with a dental mixerfor 20 seconds. 2.11 gram of deionized water was added and mixed withthe dental mixer for 20 seconds, resulting in a clear gel.

Example 7 Preparation of Microemulsion with Rake Type SPE 2

[0043] 4.02 gram of a non-crosslinked and long chain or high molecularweight silicone polyether of the formula MD_(196.6)D′_(63.4)M wherein Mis (CH₃)₃SiO—, D is (CH₃)₂SiO═, and D′ represents(CH₃)[(CH₂)₃₀(CH₂CH₂O)₇H]SiO═, and 2.4 gram of volatile silicone oil D5,were loaded into a plastic container and mixed with a dental mixer for20 seconds. 3.61 gram of deionized water was added and mixed with thedental mixer for 20 seconds, resulting in a clear gel.

[0044] The microemulsions prepared according to the invention can beused in various over-the-counter (OTC) personal care products. Thus,they can be used in antiperspirants, deodorants, skin creams, skin carelotions, moisturizers, facial treatments such as acne or wrinkleremovers, personal and facial cleansers, bath oils, perfumes, colognes,sachets, sunscreens, pre-shave and after-shave lotions, liquid soaps,shaving soaps, shaving lathers, hair shampoos, hair conditioners, hairsprays, mousses, permanents, depilatories, cuticle coats, make-ups,color cosmetics, foundations, blushes, lipsticks, lip balms, eyeliners,mascaras, oil removers, color cosmetic removers, and powders. Themicroemulsion compositions are also useful as carriers forpharmaceuticals, biocides, herbicides, pesticides, and to incorporatewater and water-soluble substances into hydrophobic systems.

[0045] Other variations may be made in compounds, compositions, andmethods described herein without departing from the essential featuresof the invention. The embodiments of the invention specificallyillustrated herein are exemplary only and not intended as limitations ontheir scope except as defined in the appended claims.

1. A method comprising spontaneously forming a clear microemulsionwithout mixing, stirring, shearing, or input of mechanical energy foragitating ingredients used in making microemulsions, by simply combiningas ingredients (i) water; (ii) a volatile siloxane; (iii) a long chainor high molecular weight silicone polyether; and, as an optionalingredient, (iv) a cosurfactant selected from the group consisting of amonohydroxy alcohol, an organic diol, an organic triol, an organictetraol, a silicone diol, a silicone triol, a silicone tetraol, and anonionic organic surfactant; the long chain or high molecular weightsilicone polyether (iii) having formula

where R1 represents an alkyl group containing 1-6 carbon atoms; R2represents the radical —(CH₂)_(a)O(C₂H₄O)_(b)(C₃H₆O)_(c)R3; x is20-1,000; y is 2-500; z is 2-500; a is 3-6; b is 4-20; c is 0-5; and R3is hydrogen, a methyl radical, or an acyl radical.
 2. A method accordingto claim 1 in which volatile siloxane (ii) is a volatile linear methylsiloxanes of the formula (CH₃)₃SiO{(CH₃)₂SiO}_(k)Si(CH₃)₃ where k is0-5; or a cyclic methyl siloxane of the formula {(CH₃)₂SiO}_(t) where tis 3-9; the volatile siloxane having a boiling point less than about250° C., and a viscosity of 0.65-5.0 mm²/s.
 3. Clear microemulsionsprepared according to the method defined in claim
 1. 4. A methodcomprising spontaneously forming a clear microemulsion without mixing,stirring, shearing, or input of mechanical energy for agitatingingredients used in making microemulsions, by simply combining asingredients (i) water; (ii) a volatile siloxane; (iii) a non-volatilesiloxane; (iv) a long chain or high molecular weight silicone polyether,or a short chain or low molecular weight silicone polyether; and, as anoptional ingredient, (v) a cosurfactant selected from the groupconsisting of a monohydroxy alcohol, an organic diol, an organic triol,an organic tetraol, a silicone diol, a silicone triol, a siliconetetraol, and a nonionic organic surfactant.
 5. A method according toclaim 4 in which silicone polyether (iv) is a long chain or highmolecular weight silicone polyether having formula

where R1 represents an alkyl group containing 1-6 carbon atoms; R2represents the radical —(CH₂)_(a)O(C₂H₄O)_(b)(C₃H₆O)_(c)R3; x is20-1,000; y is 2-500; z is 2-500; a is 3-6; b is 4-20; c is 0-5; and R3is hydrogen, a methyl radical, or an acyl radical.
 6. A method accordingto claim 4 in which volatile siloxane (ii) is a volatile linear methylsiloxanes of the formula (CH₃)₃SiO{(CH₃)₂SiO}_(k)Si(CH₃)₃ where k is 0-5or a cyclic methyl siloxane of the formula {(CH₃)₂SiO}_(t) where t is3-9; the volatile siloxanes have a boiling point less than about 250° C.and a viscosity of 0.65-5.0 mm²/s.
 7. A method according to claim 6 inwhich non-volatile siloxane (iii) is a nonvolatile linear or cyclichigher alkyl or aryl siloxane of the formula R^(a) ₃SiO(R^(a)₂SiO)_(p)SiR^(a) ₃ or (R^(a) ₂SiO)_(r) where R^(a) is an alkyl groupwith 1-20 carbon atoms or an aryl group, hydrogen, an aralkyl(arylalkyl) group, or an alkaryl (alkylaryl) group; p is 0-375; r is3-9; and the non-volatile siloxane has a viscosity greater than fivemm²/s to 1,000 mm²/sec.
 8. Clear microemulsions prepared according tothe method defined in claim 4.